Toric lenses alignment using pre-operative images

ABSTRACT

Proper selection and centering of an intraocular lens (IOL) is provided. An image of an eye, which may be captured during pre-operative tests and provided to a program operable to calculate the power and axis orientation of the IOL, is used to determine the location and orientation of the IOL. This produces an output or placement guide used to properly center and orient an IOL within the eye.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to U.S.Provisional Patent Application No. 60/955,528, filed Aug. 13, 2007, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to the field of intraocularlenses (IOL), and, more particularly, to methods and systems fordetermining placement and orientation of an implanted IOL.

BACKGROUND OF THE INVENTION

The human eye in its simplest terms functions to provide vision bytransmitting light through a clear outer portion called the cornea, andfocusing the image by way of the lens onto the retina. The quality ofthe focused image depends on many factors including the size and shapeof the eye, and the transparency of the cornea and lens.

When age or disease causes the lens to become less transparent, visiondeteriorates because of the diminished light which can be transmitted tothe retina. This deficiency in the lens of the eye is medically known asa cataract. An accepted treatment for this condition is surgical removalof the lens and replacement of the lens function by an artificialintraocular lens (IOL).

In the United States, the majority of cataractous lenses are removed bya surgical technique called phacoemulsification. During this procedure,a thin phacoemulsification cutting tip is inserted into the diseasedlens and vibrated ultrasonically. The vibrating cutting tip liquefies oremulsifies the lens so that the lens may be aspirated out of the eye.The diseased lens, once removed, is replaced by an artificial lens.

The placement of an IOL is very important in order to ensure the bestpossible vision for patient's with cataracts. Oftentimes there is not agood feedback process during surgery to ensure that the IOL is properlyplaced and oriented within the eye.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a system and methodoperable to provide for the proper selection and centering of anintraocular lens (IOL) that substantially addresses the above identifiedneeds. An image of an eye, which may be captured during pre-operativetests and provided to a program operable to calculate the power and axisorientation of the IOL, is used to determine a location and orientationof the IOL. A placement guide is produced for use in properly centeringand orienting an IOL within the eye.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following descriptiontaken in conjunction with the accompanying drawings in which likereference numerals indicate like features and wherein:

FIG. 1 depicts selected tissues of the eye;

FIG. 2 depicts various inputs which may be used by an IOL calculatingcomputer program to calculate the power of a “toric lens,” and thelocation and axis orientation of that IOL lens used to replace lenstissue within eye in accordance with embodiments of the presentinvention;

FIGS. 3, 4 and 5 present different ways in which information may be usedto generate placement guides in accordance with embodiments of thepresent invention;

FIG. 6 depicts a system operable to facilitate placement of an IOL inaccordance with embodiments of the present invention; and

FIG. 7 provides a logic flow diagram in accordance with embodiments tothe present invention of a process operable to place an IOL within aneye.

DESCRIPTION OF THE INVENTION

Preferred embodiments of the present invention are illustrated in theFIGs., like numerals being used to refer to like and corresponding partsof the various drawings.

Embodiments of the present invention substantially address the aboveidentified needs as well as others. Intraocular Lenses (IOL) have openednew possibilities for treating cataractous lenses which are removed by asurgical technique. The diseased lens, once removed, is replaced by anartificial lens. Proper vision following the procedure depends greatlyon the placement and orientation of the IOL.

FIG. 1 depicts selected tissues of eye 10. These include the iris,pupil, cornea and lens which, when cataractous, may be removed andreplaced with an IOL. The placement of an IOL is a key component to thebest possible vision for the patient.

FIG. 2 depicts various inputs which may be used by a computer program,IOL calculating program 32, to calculate the power of a toric lens, andthe location and axis orientation of that IOL lens used to replace lenstissue within eye 10. These inputs include pre-operative tests 22 usedto determine the center of the eye, video or digital cameras 24 used toproduce eye images with sclera vessels, and cornea topographer 26.Incision location information and surgically induced astigmatisminformation 28, and white-to-white dimension 30 are also provided. Themeasured data along with these representations of the eye along withincision location information may be used by program 32. In oneembodiment, IOL calculation program 32 may be Alcon's “toric calculator”that is executed on a desktop computer or cataract removal console suchas Alcon's “Infiniti Vision System.” The image of the eye capturedduring pre-operative tests may be uploaded into (provided to) softwareprogram 32.

These inputs are used by IOL calculating program 32 to produce an imageor like representation of the eye with the location and orientation axisof the IOL identified. Knowing the center of the eye is keenly importantfor the proper centering and alignment of an IOL.

FIGS. 3, 4 and 5 discuss different ways in which this information may beused. In FIG. 3 software program 32 may provide an output such as asimple printed picture in process 34 that becomes available to a surgeonduring surgery. This allows a surgeon to reference the image andcharacteristic vessels therein to locate the incision and orient the IOLin process 36.

FIG. 4 describes another possibility for how location and orientationinformation may be applied. Again software program 32 produces oroutputs orientation and location information. In this instanceorientation and location information may be printed on a transparentmaterial which may include a contact lens in process 38. This image onthe transparent material may be overlaid by the surgeon directly on thepatient's eye to match the characteristics of the patient's eye withinprocess 40. The IOL may then be centered and rotated to match markers onthe transparent material.

A third process is depicted in FIG. 5. Here software program 32 providesan electronic output which may be uploaded on a lens removal console 42.The console may receive video from an optical microscope whichrecognizes vessels and overlays live optical video images in process 44to previously uploaded pre-operative images. The video information maythen be used to advise the surgeon in how to rotate and place the IOL.

FIG. 6 depicts a system operable to facilitate placement of an IOL.System 60 includes Corneal topographer 62 equipped with a digital camera64 to produce a surface profile and image of eye 10 that includesvessels in the sclera. Alternatively a separate camera 66 can be used totake the picture of patient's eye 10. Data from the topographer 62 alongwith incision location and induced astigmatism are input into program 32to calculate power of the toric lens and the axis orientation. Theprogram can reside on the web, on an office PC, or on the cataractremoval console such as the Infiniti Vision System (Alcon). The image ofthe eye captured during preoperative test 68 at the same time whentopography was performed, or at least in the same patient orientation,is uploaded into the same program. The output is the image of the eyewith the axis overlaid. It is also possible to label the “center” of theeye on the same image, however determined during the preoperative tests.The center of the eye is important for proper centering of IOL.

The image of the eye 10 with the vessels, overlaid steep axis of thetoric lens and the center of the eye 10, as well as approximate “up”arrow can then be used in three ways to generate reference diagrams asdescribed in FIGS. 3-5.

Embodiments of the present invention may take advantage of computerImage analysis of digital images of the eye taken during a pre-surgerysession and again during the surgical procedure to register the eye, anda microscope adapted with a heads-up display (HUD) to provide thesurgeon with visual feedback to help orient visually the IOL during theimplantation procedure.

Digital image analysis allows measurements taken during the pre-surgerysession by a corneal topographer to facilitate selecting the IOL'soptical characteristics. The selection of IOL cylinder power is made onthe basis of corneal topography measurements as well as other anatomicmeasurements of the eye, such as eye length and anterior chamber depth.As part of the topography measurement, a video snapshot of the eye canbe captured with a camera incorporated into the topographer and situatedat a known position and orientation with respect to the eye andtopographic measurement apparatus such that precise “mapping” of thesnapshot of the eye to the corneal topography measurement can be made.

The camera, camera optics, camera electronics and eye illuminationsystem can be chosen to allow video snapshots of the eye to be takensimultaneously with the topographic measurement (to prevent eye motionartifacts) and to permit an mage of sufficient contrast, resolution andfield of view to allow clear visibility of scleral blood vessels andother eye features such as the limbus.

First, the image can be simply printed out and posted in front of thesurgeon during the surgery. The surgeon can then referencecharacteristic vessels to position an incision appropriately and toorient the IOL relative to the scleral blood vessels. This may obviatethe need for manual eye marking with a “sharpie” as typically done inthe prior art, but will likely provide rather limited accuracy.Pre-operative biometry information along with the eye's image is inputinto the program which calculates optimum toric lens and its orientationin the eye.

Second, the image of the eye including the steep axis and location ofthe incision can be printed out on a transparent plastic, for exampletransparencies or a contact lens. In order to scale the image properly,the “white-to-white” dimension input into the program is used. The toniclens is implanted into the eye and oriented approximately. There is apattern printed on the lens which indicates direction of the axis. Forexample, 3 dots in the peripheral part of the optic may be used toindicate the axis. After the lens is placed and approximately oriented,the transparent plastic is overlaid on the eye and oriented to matchvessels. Then the lens is centered and oriented so that the axis markedon the lens is superimposed with the axis printed on the plastic withthe lens superimposed with the “center” printed on the plastic.

Another method is to upload the image of the eye with the vessels, axisand center onto the lens removal console. An image from the surgicalmicroscope is transferred to the console as well and compared with theuploaded image. Sclera vessels serve as landmarks to overlay the twoimages. Lens orientation is determined by locating the distinguishingfeatures on the lens. The surgeon is presented with the captured imageof the eye on the screen of the console and advised visually and/orthrough voice confirmation where to move and/or rotate the lens. Thereare other advantages in having the eye image and biometry informationinput into the console. At the beginning of the procedure there can be astep on the console for providing supplementary information to thesurgeon relating to where to make an incision and information onincision width. If the location or width of the incision are altered,the new information can be input back into the console to analyzepotential differences in recommended lens selection and/or lensorientation. This can be easily accomplished if the IOL calculationprogram 32 is loaded on the console. The console can also be equippedwith a barcode reader, or other equipment tracking system, and the IOLand tools (e.g., knife) used in surgery can be scanned so that theconsole can double check the incision width as well as the lensselection.

FIG. 7 provides a logic flow diagram in accordance with embodiments tothe present invention of a process operable to place an IOL within aneye. Operations 70 begin with Step 72 where an image or otherinformation about an eye in which the IOL is to be implanted iscaptured. Additionally planned incision location information and inducedastigmatism information as well as white-to-white measurements may becaptured as well. In Step 74 the captured information may be uploaded(provided) to an IOL calculator. This IOL calculator in Step 76 maycalculate the power of the IOL as well as the location and orientationof the IOL within the eye. In Step 78 a surgical guide or placementguide may be generated to facilitate placement of the IOL within theeye. This placement guide may be a simple photograph available to thesurgeon so that the surgeon may reference a picture and characteristicstherein to locate the incision and orient the lens. Alternatively thisplacement guide may take the form of a transparent material, such as acontact placed over the eye, wherein placement guide information isprinted on the transparent material. The transparent placement guide canthus be overlaid directly on the patient's eye by the surgeon in orderto match the actual vessels there. The lens may then be centered androtated to match markers on the transparent material.

Alternatively, the placement guide may be electronic and overlaid withreal time video information. The video information may be captured by asurgical microscope and transmitted to a lens removal console whereinprocessing modules within the lens removal console recognize and matchstructures from the placement guide to the live images. The lens removalconsole can recognize the lens marks and advise the surgeon on how torotate and place the lens. In Step 80 the IOL is placed with the aid ofthe surgical or placement guide wherein the placement of the IOL mayalso be verified.

In summary, embodiments of the present invention provide for the properselection and centering of an intraocular lens (IOL). An image of aneye, which may be captured during pre-operative tests and provided to aprogram operable to calculate the power and axis orientation of the IOL,is used to determine the location and orientation of the IOL. Thisproduces an output or placement guide that can be used to properlycenter and orient an IOL within the eye.

As one of average skill in the art will appreciate, the term“substantially” or “approximately”, as may be used herein, provides anindustry-accepted tolerance to its corresponding term. Such anindustry-accepted tolerance ranges from less than one percent to twentypercent and corresponds to, but is not limited to, component values,integrated circuit process variations, temperature variations, rise andfall times, and/or thermal noise. As one of average skill in the artwill further appreciate, the term “operably coupled”, as may be usedherein, includes direct coupling and indirect coupling via anothercomponent, element, circuit, or module where, for indirect coupling, theintervening component, element, circuit, or module does not modify theinformation of a signal but may adjust its current level, voltage level,and/or power level. As one of average skill in the art will alsoappreciate, inferred coupling (i.e., where one element is coupled toanother element by inference) includes direct and indirect couplingbetween two elements in the same manner as “operably coupled”. As one ofaverage skill in the art will further appreciate, the term “comparesfavorably”, as may be used herein, indicates that a comparison betweentwo or more elements, items, signals, etc., provides a desiredrelationship. For example, when the desired relationship is that signal1 has a greater magnitude than signal 2, a favorable comparison may beachieved when the magnitude of signal 1 is greater than that of signal 2or when the magnitude of signal 2 is less than that of signal 1.

Although the present invention is described in detail, it should beunderstood that various changes, substitutions and alterations can bemade hereto without departing from the spirit and scope of the inventionas described.

What is claimed is:
 1. Software embodied in a computer-readable mediumcapable upon execution of providing a placement guide for an IOL byperforming the following steps: capturing information associated with aneye in which an IOL is to be implanted; capturing incision locationinformation and induced astigmatism information associated with the eyein which an IOL is to be implanted; providing the information to an IOLcalculating software program operable to calculate a location andorientation of the IOL within the eye; and generating a placement guideoperable to assist a surgeon in placing the IOL within the eye.
 2. Themethod of claim 1, further comprising using the placement guide toverify placement of the IOL within the eye.
 3. The method of claim 1,wherein the information associated with the eye comprises a surfaceprofile and/or image of the eye, wherein the image includes vesselswithin the sclera.
 4. The method of claim 3, wherein a cornealtopographer coupled to a digital camera captures the surface profileand/or image.
 5. The method of claim 1, wherein the placement guidecomprises an image that a surgeon may reference to position the incisionand the IOL.
 6. The method of claim 1, wherein the placement guidecomprises an image on transparent material that a surgeon may referenceto position the incision and the IOL.
 7. The method of claim 6, whereinthe image is located on a contact lens operable to be placed on the eye.8. The method of claim 1, wherein the placement guide comprises anplacement guide image combined with an image from a surgical microscope,within a lens removal console.
 9. The method of claim 8, wherein thelens removal console is operable to advise the surgeon placing the IOL.10. Software embodied in a computer-readable medium capable uponexecution of providing a placement guide for an IOL by performing thefollowing steps: capturing information associated with an eye in whichan IOL is to be implanted; capturing planned incision locationinformation associated with the eye in which an IOL is to be implanted;capturing-induced astigmatism information associated with the eye inwhich an IOL is to be implanted; providing the information to an IOLcalculating software program operable to calculate a location andorientation of the IOL within the eye; calculating the location andorientation of the IOL within the eye; and generating a placement guideoperable to assist a surgeon in placing the IOL within the eye.
 11. Themethod of claim 10, further comprising: providing the surgeon feedbackassociated with the location and orientation of the IOL within the eye;and using the placement guide to verify placement of the IOL within theeye.
 12. The method of claim 10, wherein the information associated withthe eye comprises a surface profile and/or image of the eye, wherein theimage includes vessels within the sclera.
 13. The method of claim 12,wherein a corneal topographer coupled to a digital camera captures thesurface profile and/or image.
 14. The method of claim 10, wherein theplacement guide comprises an image that a surgeon may reference toposition the incision and the IOL.
 15. The method of claim 10, whereinthe placement guide comprises an image on transparent material that asurgeon may reference to position the incision and the IOL.
 16. Themethod of claim 15, wherein the image is located on a contact lensoperable to be placed on the eye.
 17. The method of claim 10, whereinthe placement guide comprises an placement guide image combined with animage from a surgical microscope, within a lens removal console.
 18. Themethod of claim 17, wherein the lens removal console is operable toadvise the surgeon placing the IOL.
 19. A lens removal console operableto facilitate placement of an intraocular lens (IOL), comprising: atleast one input port operable to receive: information associated with aneye in which an IOL is to be implanted; planned incision locationinformation associated with the eye in which an IOL is to be implanted;and induced astigmatism information associated with the eye in which anIOL is to be implanted; a processing module and associated memorycoupled to the at least one input port, the processing module operableto execute an IOL calculating software program operable to: calculate alocation and orientation of the IOL within the eye from: the informationassociated with an eye in which an IOL is to be implanted; the plannedincision location information associated with the eye in which an IOL isto be implanted; and the induced astigmatism information; and generate aplacement guide operable to assist a surgeon in placing the IOL withinthe eye.
 20. The lens removal console of claim 19, wherein a Cornealtopographer coupled to a digital camera captures the informationassociated with the eye and wherein the information comprises vesselswithin the sclera.
 21. The lens removal console of claim 19, wherein theplacement guide comprises: an image that a surgeon may reference toposition the incision and the IOL; an image located on a contact lensthat a surgeon may reference to position the incision and the IOL;and/or a placement guide image combined with an image from a surgicalmicroscope, within the lens removal console.
 22. The lens removalconsole of claim 19, wherein the lens removal console is operable toadvise the surgeon placing the IOL.